Red Blood Cell Abnormalities in White-Blooded Icefishes and Related Antarctic Species
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Date
2023-11
Authors
Nunez, Zoe
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oregon
Abstract
The process of cell differentiation is crucial for organism viability, especially the formation of red blood cells (RBCs) that contain hemoglobin and provide essential oxygen transportation to the tissues. Antarctic white-blooded icefishes are, however, evolutionary oddities that lack mature RBCs and hemoglobin. An outstanding question is if the loss of hemoglobin genes in the icefish ancestor could have led to the arrest of RBC maturation in icefishes, or inversely if the arrest of RBC maturation could have triggered the loss of hemoglobin genes. Here, we aimed to test these two conflicting hypotheses. The ‘genes-first hypothesis’ predicts that the icefish ancestors would start to lose hemoglobin genes while having normal blood cells, but the ‘cells-first’ hypothesis predicts that icefish ancestors would have damaged RBCs but normal hemoglobin genes. To test these predictions, we analyzed the blood cell composition and RBC morphology in 13 red-blooded Antarctic fish species and in seven icefishes by microscopy, semi-automated digital image analyses, and phylogenetic comparative analyses. My investigation revealed that some species closely related to icefishes display abnormal RBCs that are larger and rounder than in other red-blooded species and have off-centered nuclei. My results suggest that RBC maturation was likely already altered before the loss of hemoglobin genes in icefishes. Close analysis of cellular abnormalities arising in these Antarctic fish species may inform us on hereditary human diseases such as anemias arising from improper RBC formation.
Description
64 pages
Keywords
evolutionary biology, cellular biology, cellular abnormalities, fish blood, Icefish